Tribromo derivatives of indigo and process of making same.



1 a not known.

40 may finally be 22()--225 (7.

. UNITED STATES PATENT ()FFIGE.

GADIENT 'ENG OF BASEL, SWITZERLAND, AssIc oa'ro THE FIRM OF SOCIETY OF CHEMICAL INDUSTRY IN BAsLE, or BASEL, SWITZERLAND.

T RlBROMO DERIVATIVES 0F INDIGO AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Application filed larch 23, 1907. Serial No. 884,019.

Patented June 11, 1907.

Swiss Republic, and a resident of Basel 5 Switzerland, have invented new and usefu Tribromo Derivatives of Indigo and a Process of Making the Same, of which the following is a full and. exact specification.

Hitherto tribromo derivatives of indi o are I have found that suc tribromo substitution products of indigo are produced in an extremely smooth manner and with ,substantially quantitative yield by treating indigo or its monoand di-bromo del 5 rivatives with suitable proportion of bromin at a raised temperature in presence ofa propriate solvents or of appropriate me ia in which the material may esuspended. The

new tribromo derivatives of indigo thus ob- 2o tained are extremely valuable dyestufi's on account of their tinctorial properties, for= they can easily be made into vats by the usual methods and dye cotton without a mordant clear blue tints, which are consid- 5 erably more vivid and of a greener shade than the. tints obtained by means of indigo or its known monoor di-bromo derivatives; moreover, as compared with the latter, the are considerably faster to washing and oh ori 0 The manufacture of these new tribron derivatives of indigo is illustrated by the. followingexam lcs.

Example 5 parts of indlgo are sus bath in which the containing vessel is heated Much hydrogen bromid is ev olved and the product of the reaction gradually scparates as well formed crystals. After heating for another 1% hours, the whole is cooled, the brominated .5 product, which has separated almost quantitatively, is drained, washed with alcohol and dried; .it then forms a violet-brown crysv talline owde'r and is a tribromindigo, (C ll 131 It dissolves in concen- 5otrated sulfuric acid with a greenish blue coloration, and in fuming sulfuric acid containing 24 per cent S0,, with a deep blue colorationi ()n pouring this latter so u 'lution.

tion into 1 sparingly soluble in cold ani'in and cold nitrobenzene to ,a blue solution, but dissolves somewhat more in hot anilin and hot nitrm benzene, the solution-in nitrobenzene beingbluish-violet and the solution in anilin showin a blue coloration. It is very s aringly so uble in chloroform to a greenish blue so- When treatedwith alkaline reducing agents it yields easily and smoothly a greenish-yellow vat, from'which cotton without a mordant is (1 ed vivid'blue tints fast to washing and chlorin and becoming still more ure and faster to chlorin after a short soaplng at 60 C.

n the foregping example 'hnother suitable substance suc be substitutedfor nitrobenzene. xample II. 5 parts of indigo, 50 parts of ortho-nitrotoluen'e and about 16 parts of bromin are heated together in a reflux a paratus in an oil bath, the temperature o the latter being gradually raised to 180 (3.; much hydrogen bromid is evolved and after continuing to heat at this tem erature for about 1} hour, the whole is coo ed and; the product of the reaction is filtered, washed with alcohol and dried. The dyestufi thus obtained is also a tribromindigo.

Instead of brominating indigo itself, as in the foregoing examples, the manufacture of 85 tribromo derivatives of indigo may obviously be effected by further brominating the monoor dibromo substitution products. 4

Example III. 5 parts of dibromindigo, 50 parts of nitrobenzene and 2 to 2,5 parts of romin are heated in a reflux apparatus in an oil bath in the course of an hour to 225 C. and maintained during about 1% to 2 hours at a tem erature of 226 to 228 C. (temperature of t e oil bath). Much hydrogen bromid is evolved during the heating. After cooling, the se arated product of the reaction is filterer washed with alcohol and. dried and thus obtained in the form of a blue crystalline powder of a similar character as the tribromo derivative derived directly from the indigo.

What I claim is:

1. The described rocess for the manufacture of tribrorno derivatives of indigo, which process consists in heating indigo, monoand dibromindigo with bromin in the pres- 4 ice-water greenish bluo flocks separate. It is 1 ence of a suitable indifferent medium.

as glacial acetic acid, dichloroor trichlorobenzene or ortho nitrotoluene- 2. The described processfor the manufacture' of tribromo derivatives of indigo, which process consists in treating indigo, monoand dibromindigowith bromin in the presence of nitrobenz'ene. V

3. As new products, the described tribromo derivatives of indigo corresponding to the formula Q H O N B constituting in dry state from dark blue'to. brownish-violet owders, insoluble inwater, difiicultly solub e in cold anilin and nitrobenzene, more easily-in hot anilin and nitrobenzene with a blue to bluish violet color, dissolving in concentrated sulfuric acid with blue color, and .yielding yel-- l lowish vats by'treatment with ducmg agents.

.4. As anew article of manufacture, the described tribromo derivative of indigo which can be obtainedvby heating indigo with bro- ,suitable reproduct min in the presence of nitrobenzene, which dissolves in concentrated sulfuric acidwith a greenish-blue and in fuming sulfuric acid of 24 p. 0. S0 With-a deep blue color, is diHic'ultly soluble in hot anilin with a blue color and in hot nitrobenzene with a blue-violet color and yields by treatment with otassium hydrosulfite a greenish yellow in beautiful blue shades, fas't to washing,-

vat, om which unmordanted cotton is dyed light and chlorin.

In witness whereof I have hereunto signed presence of two subscribing witnesses.

Witnesses:

GEO. GIFFORD, AMAND BRAUN'.

my name this 2 day of March 1907, in the GADIENT ENG-I; v 

